利用偏振光谱研究分子偶极矩取向

有机材料分子偶极矩的取向可以影响平板OLED器件 的输出耦合效率,进而对OLED的发光效率具有重要的影响。通过测量偏振光谱及Gaussian软 件拟合,分析了提拉成膜法制备的具有不同分子构型的8-羟基喹啉铝(Alq₃)和4,4-二(9-咔唑)联苯(CBP)薄膜及其溶液中分子偶极矩的取向。实验结果和理论计算分析表明 ,Alq₃分子具有5.769 Debye的固有偶极矩 ,而CBP分子的固有偶极矩为零。在氯仿溶液中两种分子的取向随机分布,提拉成薄膜后分 子沿提拉方向具有一定程度的择优取向,呈现各向异性。薄膜中Alq₃分子的各向异性度大 于溶液状态,而CBP分子的情况正好相反。分析认为:分子是否具有固有偶极矩及偶极矩的 取向,是不同的偏振吸收和偏振荧光现象出现的原因。

Study on molecule dipole orientation based on polarized spectrum

The molecular dipole moment orientatio n of the organic material can affect the output coupling efficiency of the flat OLED device,and has an important influence on the luminous efficiency of the OLE D.The 8-hydroxyquinoline aluminum (Alq₃) and 4,4-bis (9-carbazole) biphenyl with different molecular configurations prepared by the pull-up film forming m ethod were analyzed by measuring the polarization spectrum and Gaussian software fitting.The experimental results and theoretical calculation analysis showed th at the Alq_3molecule has an intrinsic dipole moment of 5.7699Debye,while the intrinsic dipole moment of the CBP molecule is zero.The orie ntation of the two molecules are randomly distributed in the chloroform solution ,and have a certain degree of orientation along the pulling direction,showing an isotropy after pulling into film.The anisotropy of Alq3molecules in the film is greater than that in the solution,while the situation of CBP molecules is just the opposite.We think that molecules with or without intrinsic dipole moment and the dipole moment orientation have a great effect on the different polarization absorption and fluorescence phenomena.